Estimating disparity from a pair of stereo images is a technique that has been well studied with the estimated disparity being used in the extraction of further information from the stereo images. For instance, the estimated disparity can be used for depth/distance calculation. Disparity between the location of an object in each of the pair of images and the distance of the object from the camera(s) which capture the stereo images are inversely related. As such, as the distance from the camera(s) increases, the disparity decreases. Consequently, disparity estimation enables depth perception in stereo images. Specifically, using geometry and algebra, pixels in two-dimensional stereo images can be mapped as coordinates in three-dimensional space. Determining depth from two-dimensional images has many uses, not least in the field of navigation.